thanks!
the b tension screw is unscrewed as far as it will go, is that the screw you're referring to?
the chain lengthening helps..ie if i put it around the small chain ring up front then the jockey pulley is engaged on all cogs. but I was careful when I measured the chain for length, and it worked fine with a prior rd, so I want to make sure the problem isn't elsewhere before I put on a new chain.